The present invention relates to a signal quantizing circuit for a photographic camera or an exposure meter for indicating exposure information such as exposure time, object brightness, utilizing a plurality of lamps instead of an ammeter.
The ammeter, conventionally utilized for indication of exposure information, is liable to get out of order due to mechanical shocks, resulting in frequent trouble. The present invention provides an input information quantizing circuit for highly reliable indication utilizing a plurality of indicating lights or elements without movable parts, such as electric lamps, light emission diodes, etc., instead of the less reliable ammeter.
Information about several similar known devices has been published. Most of these devices utilize values indicated by a counter for quantization. According to this method, (1) the value indicated by a counter varies only by "1", so that the response time for variation of signal of constant ratio is proportional to the value, that is, a large value requires a long response time, while a small value requires a short response time; (2) the resolution of quantization is simply determined by the minimum weight bit, so that for larger values the quantization is unnecessarily minute; and (3) a relatively large scale decoder is required for indication. These are drawbacks in practical use for indication of exposure information which vary exponentially over a wide range.